Discharge device for at least one medium

ABSTRACT

1. Discharge device for at least one medium.  
     2.1. Discharge devices for at least one medium with a media reservoir, a pumping device and a discharge opening are known.  
     2.2. According to the invention the media reservoir has at least two media reservoir sections positioned rigidly relative to one another and which pass into one another in their interior through a step shoulder.  
     2.3. Use for the discharge of a medium.

[0001] The invention relates to a discharge device for at least onemedium, with a medium reservoir, a pumping device and a dischargeopening.

[0002] Numerous different constructions of such discharge devices areknown from the prior art. A discharge of one or more media, particularlypulverized solids, liquids with an aqueous to viscous consistency orgases, is of great importance in particular in numerous cosmetic andpharmaceutical sectors. The at least one medium is stored in a mediumreservoir of the discharge device and can be conveyed by a pumpingdevice from the medium reservoir through a discharge opening into theenvironment. The discharge opening is matched to the viscosity andintended use of the medium to be discharged. More particularly for mediawith a small particle size, aqueous consistency and low viscosity,frequently an atomization in the ambient air by means of a nozzle-shapedoutlet port is sought. For semiliquid, highly viscous liquids acylindrical or conical discharge opening is preferred. The pumpingdevices for discharging a medium from the media reservoir can bedesigned as a self-priming pump, where the pressure necessary fordischarge purposes is built up in the pumping device outside the mediareservoir. Other pumping devices place the media reservoir underpressuring using appropriate means and consequently bring about thedischarge of the medium through the discharge opening. Known mediareservoirs have a substantially uniform cross-section and their wallthickness is matched to the requirements of the pumping device.Discharge devices which are designed for a limited number of pumpstrokes or lifts, particularly for one or two strokes, frequently have asealed media reservoir. For this purpose the pumping device is designedin such a way that the medium to be discharged is only fed out of themedia reservoir, which has been sealed up to this time, on performingthe pump stroke. The pumping device during the first pump stroke opensthe seal of the media reservoir and places the latter under pressure.Discharge devices of this type designed for a small number of pumpstrokes are more particularly used for the administration of inoculatingagents. As the pumping device only has to be operated one or two timesand the discharge device for hygienic reasons is then disposed of, thereis a great interest in a particularly inexpensive, but reliabledischarge device. The prior art discloses various solutions for thispurpose and they have in particular a plastic media reservoir. A plasticmedia reservoir is in particular characterized by low manufacturingcosts, but suffers from disadvantages with regards to long-termstability and sealing action. The storability of the stored medium isinfluenced both by diffusion processes and the quality of the sealingsurfaces. These disadvantages are more pronounced with media reservoirscontaining two different media, particularly a liquid medium and a solidmedium. With such media reservoirs particularly high demands are made onthe sealing area between the solid and liquid media. Only in this way isit possible to prevent a degeneration of the two separate constituents.Known solutions are unable to provide a completely satisfactoryresponse.

[0003] The problem of the invention is therefore to provide a dischargedevice of the aforementioned type, which permits an improved mixing ofseveral media and a good dosability of at least one medium for adischarge.

[0004] This problem is solved in that the media reservoir has at leasttwo, mutually rigidly positioned media reservoir sections, which passinto one another in the interior thereof through a step shoulder. Themedia reservoir is subdivided into at least two media reservoirsections, which have different cross-sections and are positioned rigidlyrelative to one another by a fixed connection. The cross-section changebetween the two media reservoir sections occurs in the form of a stepshoulder, which produces the transition between the at least twodifferent cross-sections. With a particular planar surface the stepshoulder bridges a sudden cross-section change between the two differentcross-sections of the media reservoir sections. Thus, particularly inconjunction with at least one pump piston section associated with themedia reservoir section, it is possible to bring about a precise dosingand a particularly good miscibility of the at least two media.

[0005] According to a development of the invention, the step shoulderhas a sharp, circumferential edge. Between the media reservoir sectionsthe sudden cross-section change is bridged by the step shoulder. At atransition point between the in particular areal step shoulder and theinner face of the media reservoir section having the smallercross-section, the inner face of the media reservoir section penetratesthe face of the step shoulder, the two faces passing into one anotheralong a cutting edge. As a function of the design of the two previouslydescribed faces, said cutting edge is placed in a plane or in space andin particular with a cylindrical inner face and a planar step shoulder aplanar, circular cutting edge is obtained, the two faces being inparticular at an angle of 90σ to one another. A sharp edge between thetwo faces can in particular be implemented in an angular range of 20 to135σ, preferably 80 to 110σ. The sharp edge ensures a particularly goodseating of a sealing agent provided in this area. Moreover, as a resultof the sharp edge, particularly when using the media reservoir forstoring at least two different media, a particularly advantageousthorough mixing of the corresponding media results from the hydrauliccharacteristics of such an edge. A particularly precise dosing can beobtained when there is only a single medium.

[0006] According to a further development of the invention, the mediareservoir sections are formed by two separate hollow bodies, which aresuperimposed over a portion of their length and which are tightlyinterconnected in the superimposing area. Through the construction ofthe media reservoir sections as separate hollow bodies, it is possibleto use different media reservoir section materials for the media to bestored. Thus, the materials can in particular be matched to the needs ofthe particular medium. In order to create a unitary media reservoir thecorresponding hollow bodies are superimposed over a portion of theirlength and tightly interconnected in the thus formed superimposing area.

[0007] According to a further development of the invention, at least onemedia reservoir section is produced from a crystalline or amorphousmaterial and has an almost smooth inner wall. Crystalline and amorphousmaterials, particularly metals, ceramics or glasses, are particularlysuitable for the long-term storage of media. As a result of their highdensity, they only allow an extremely small diffusion between the mediumto be stored, the media reservoir material and the environment. Inaddition, such materials behave inertly with respect to the media to bestored. Even when the filled media reservoir is stored for a long time,there is only a limited risk of the medium interacting with the mediareservoir material. Another advantage of such materials is that they canbe manufactured with almost smooth inner walls by means of inexpensive,large quantity production processes. Thus, there is a marked reductionin the active surface for an interchange between the medium and themedia reservoir section material. This also brings about a particularlyadvantageous seating of the sealing elements. Another advantage of asmooth inner wall becomes apparent during the discharge process,particularly if at least one media reservoir section is also used as apump cylinder. A smooth inner wall contributes to a particularly lowfriction, efficient pumping movement of the pump piston, which is moreparticularly constructed as a sealing element.

[0008] According to a further development of the invention, an outercontour of the inner hollow body is at least stagewise matched to aninner contour of the outer hollow body. Through the matching of theouter contour of the inner hollow body to the inner contour of the outerhollow body, particularly when using ISO tolerance ranges, it ispossible to bring about a reliable and advantageous fitting, as well asa reliable sealing action between the two media reservoir sections.Moreover and in particular when using an amorphous material such asglass, it is possible to ensure during the fitting of the mediareservoir sections that no inner stresses and strains occur, which couldbring about damage to the media reservoir sections or which could impairthe sealing action of the superimposing area.

[0009] According to a further development of the invention, the at leasttwo hollow bodies are integrally joined in the superimposing area andthis can in particular be brought about by fusing, soldering or bondingthe materials of the media reservoir sections. The fusion of thematerials of the media reservoir sections more particularly takes placeby the supply of thermal energy using an open flame, electric arc,frictional heat, laser light or induction. In soldering processes use ismade of a filler material with a melting point below that of the meltingpoints of the materials to be connected and which can be introduced intoa capillary gap of the superimposing area by heating the media reservoirsections. For bonding the media reservoir sections use is moreparticularly made of a one or two-component adhesive, which can beactivated and cured anaerobically, by external energy supply, bychemical reaction with a curing agent, by air or moisture contact or byfurther mechanisms.

[0010] According to a further development of the invention, at least thesuperimposing area of at least one hollow body is cylindrically shapedand in particular has a scarf joint. The cylindrical design of thesuperimposing area of at least one hollow body represents a particularlyinexpensively producible geometry for a media reservoir section. Furtheradvantages are associated with the connection to the adjacent mediareservoir section. A cylindrical design avoids stress peaks in the mediareservoir sections to be connected and consequently reduces the crackingand leaking risks. A scarf joint of the cylindrically shapedsuperimposing area of the media reservoir section is in particularbrought about by a conical design of the superimposing area. At thefront face facing the other media reservoir section, the cone has asmaller diameter and with increasing distance from the other mediareservoir section a diameter increase takes place.

[0011] According to a further development of the invention, each mediareservoir section has a chamber for in each case one medium which isseparate from the adjacent media reservoir section. Thus, the mediareservoir is able to store two completely different media, particularlyin a liquid, solid or gaseous aggregate state, which are intermixed onlyat the time of discharge. For this purpose, level with the stepshoulder, the media reservoir is separated into two chambers by means ofa sealing element. Particularly as a result of the sharp,circumferential edge associated with the step shoulder, as well as thealmost smooth inner wall of at least one media reservoir section, aparticularly advantageous sealing action is obtained. During a dischargeprocess said sealing element is moved from a sealing position moreparticularly into one of the chambers of the media reservoir and as aresult the desired thorough mixing of the at least two different mediain the media reservoir takes place. The media mixture can then bedelivered through the discharge opening to the environment. As a resultof the sharp edge of the step shoulder the mixing action is assisted andcan therefore be ensured in a short time period. As a function of theparticular application, it is possible to provide both liquid and solidmedia in the media reservoir sections and which as a function of themixing ratio can be introduced into the media reservoir sections whosevolumes have been correspondingly adapted.

[0012] According to a further development of the invention on an innerwall of a media reservoir section facing the media chamber in at leastone sealing area is provided a circumferential shape for receiving an atleast stagewise spherical sealing element. Such sealing elements are inparticular made from elastomeric materials and, particularly duringsealing fitting, offer advantages compared with areal sealing elementswith a cylindrical cross-section. This in particular results from thespherical shape, which permits an easy introduction of the sealingelement into the shape provided in the sealing area. An at leaststagewise spherical sealing element is virtually neutral with respect toan orientation relative to the sealing area. The circumferential shapein the sealing area on the inner wall of the media reservoir section canin particular be in the form of a groove or projection arrangement. Theat least stagewise spherical sealing element engages stagewise andpositively in the sealing area.

[0013] According to a further development of the invention, as hollowbodies are provided concentrically positioned, cylindrical glass tubesections, which are in particular laser welded together in thesuperimposing area. Glass tube sections can be industriallyinexpensively produced with extremely precise cross-sections and can beobtained in virtually random quantities. An individual adaptation of thecylindrical glass tube sections in the superimposing area during fittingis unnecessary in view of the high accuracy to size and low tolerancesof such hollow bodies. This makes it possible to bring about aparticularly good superimposing of the media reservoir sections withextremely limited additional costs. By making the media reservoir fromcylindrical glass tube sections, this brings about on a long term basisan extremely good sealing action, both with respect to the sealingelements in the superimposing area and with respect to the sealingelements located frontally on the hollow body ends. The integral jointbetween the media reservoir sections can in particular be produced ingastight manner with high process reliability using laser welding. Theproduction of this joint also has no effect on the accuracy to size ofthe media reservoir, because when using a laser welding process only theouter marginal zones of the media reservoir sections to be joinedtogether are melted. The inner areas of the cylindrical glass tubesections are not subject to a melting action and therefore suffer nodeformation. This feature can be advantageously combined with that of ascarf joint.

[0014] According to a further development of the invention, on thepumping device is provided at least one force-limited retention device,which prevents a pump stroke below a defined force level. In order toprevent an undesired actuation and an inadequate pressure build-up inthe media reservoir, a force-limited retention device is provided on thepumping device. For a pump stroke the user must place the dischargedevice under pressure, particularly by the force of a finger. Only onexceeding a previously defined force level is the pump stroke releasedby the retention device, so that as a result of the inertia of a systemformed by the discharge device and the fingers of the user, it is notpossible to drop below a clearly defined pump stroke speed.Force-limited retention devices can in particular be implemented in theform of locking or stop edges or tear-off elements.

[0015] According to a further development of the invention, there areforce-limited retention devices with different locking forces for aclearly defined sequence of individual pump stroke steps. Through suchforce-limited retention devices, it is possible to ensure that a plannedoperating sequence in the discharge device is precisely respected andconsequently the thorough mixing of the different media necessary in thecase of media reservoirs with two or more separate chambers takes placecorrectly. The different locking forces are implemented by a differentdesign of the retention devices and in particular by combining a lockingedge with a tear-off element a reliable differentiation of differentlocking forces can be obtained. This leads to a planned, controlled pumpstroke sequence. In particular, the locking force of the retentiondevice in the form of a locking edge is firstly overcome and iscompleted by one or more steps of a first pump stroke phase. Onlysubsequently is the locking force of the retention device in the form ofa tear-off element exceeded and a second discharge stroke phasecompleted.

[0016] Further advantages and features of the invention can be gatheredfrom the claims and the following description of a preferred embodimentof the invention with reference to the attached drawings, wherein show:

[0017]FIG. 1A view of a diagrammatic sectional representation of adischarge device with a media reservoir.

[0018]FIG. 2A sectional representation of a second embodiment of adischarge device with a media reservoir.

[0019]FIG. 3A sectional representation of a media reservoir of thesecond discharge device embodiment.

[0020] A discharge device 1 diagrammatically shown in FIG. 1 has a body2, which incorporates all the further components of the discharge deviceor at least stagewise encircles the same. At an end located in thedischarge direction 33 the body 2 has a nozzle shaft 11, as well as adischarge opening in the form of a nozzle 10. In the present embodimentthe nozzle shaft 11 is in particular in the form of a nose olive and hasa substantially rounded, conical section-like contour. At an end remotefrom the discharge direction 33 the body 2 is equipped with an at leaststagewise circumferential finger rest 13. The finger rest 13 is providedin order to bring about a relative movement between the body 2 and apressure sleeve 5, particularly as a support surface for an index fingerand middle finger of a user. For producing the force necessary for apump stroke, the thumb of the user is placed on a base surface 14 of thepressure sleeve 5. This permits a force flow between the finger rest 13,body 2, further components of the discharge device 1 and the hand of theuser. The pump stroke and therefore the discharge of the medium or mediais brought about by the relative movement between the body 2 and thepressure sleeve 5.

[0021] The pressure sleeve 5 is positively locked in the interior of thebody by means of an outer locking cone 22, which on fitting thedischarge device is shoved through a flexible inner locking cone 23 ofthe body 2. The positive engagement of the pressure sleeve 5 prevents adisassembly from the body 2. Movement of the pressure sleeve 5 in thedischarge direction 33 is not limited by the positive engagement betweenpressure sleeve 5 and body 2. During the discharge movement, the outerlocking cone 22 of the pressure sleeve 5 is guided along a guide bush 29of the body 2 and consequently permits a straight movement of thepressure sleeve 5 relative to the body 2. The pressure sleeve 5 has asubstantially cup-shaped cross-section and on the bottom of thecup-shaped cross-section is provided a centrally positioned solid ram 15passing out of the bottom surface. The solid ram is in a rest positionof the pressure sleeve 5 directly in engagement with an outer seal 8 ofthe solid reservoir 6.

[0022] The solid reservoir 6 is a media reservoir section produced froma cylindrical glass tube section and which is connected in gastightmanner by means of a superimposing area 31 and a connecting area 27 inthe form of a laser weld to a further media reservoir section in theform of a liquid reservoir 4. The solid 17 stored in the solid reservoir6 is separated by an inner seal 7 provided in the discharge direction ona front face of the solid reservoir 6 spaced from the outer seal 8, froma liquid medium 16 contained in the liquid reservoir 4. The inner seal 7is supported on a cylindrical surface 35 of the solid reservoir 6 actingas a sealing surface. On the front face of the solid reservoir 6 is alsoprovided a media reservoir edge 32 resulting from the cross-sectiondifference between the liquid reservoir 4 and solid reservoir 6 andlocated at an inner area of the step shoulder 34. The solid reservoir 6is jointed in the liquid reservoir 4, which cannot be gathered from thedrawing.

[0023] The liquid reservoir 4 stores a liquid medium 16, which is sealedby a piston packing 3 at a front face facing the discharge opening 10.The piston packing is supported on a cylindrical surface 24 of theliquid reservoir 4 and as a result of its geometry and the limitedroughness of the cylindrical surface 24 can be easily displaced duringthe discharge process. Immediately above the piston packing 3 the riserpipe 6 is engaged in the body 2, being supported by a liquid ram 18 in aportion of the body 2 facing the media reservoir and which is providedon its front face facing the media reservoir with a riser pipe cuttingedge 19.

[0024] Before a pump stroke can be performed, by applying a forcebetween the finger rest 3 and the pressure surface 14, the user mustexert a minimum pressure defined by the force-limited retention devicein the form of locking edge 20. Only after overcoming the locking edge20 is it possible for there to be a discharge movement of the pressuresleeve 5 and the media reservoir relative to the basic casing. At thestart of the discharge stroke, the riser pipe cutting edge 19 cutsthrough a tapered area of the piston packing 3. As soon as the riserpipe 9 has completely penetrated the piston packing 3 and is embracedall-round by it, the liquid ram 18 with its piston pressure surface 26comes into contact with the piston packing 3 and places the mediareservoir under pressure by means of the force exerted by the user. As aresult of the force exerted by the user, at the same time the solidreservoir 6 is also placed under pressure by the force on pressuresurface 14 transferred via solid ram 15 to outer seal 8. As a result theinner seal 7 is shoved into the liquid reservoir 4 and brings about acomplete mixing of solid 17 and liquid medium 16. In the presentembodiment the discharge device 1 is in the form of a disposable device,i.e. the media 16,17 stored in the media reservoir chambers areintermixed by a single pump stroke and by the discharge device nozzle 10are delivered through the media channel 12 of riser pipe 9 in dischargedirection 33.

[0025] Diverging from the discharge device shown in FIG. 1, FIG. 2 showsan actual embodiment of the discharge device 1 a. In the followingdescription details are only provided concerning the differencescompared with FIG. 1. In the case of the discharge device 1 a shown inFIG. 2, between the body 2 a and pressure sleeve 5 a is provided anadditional intermediate sleeve 37 a. On an inner guide face 38 a, theintermediate sleeve 37 a is provided on an end facing the pressuresleeve 5 a with a locking recess 39 a, which together with a lockingcollar 40 a of the pressure sleeve 5 a forms a first, positively acting,force-limited retention device. On a side facing the body 2 a, theintermediate sleeve 37 a is provided with a circumferential collar web41 a, which has an inner locking cone 23 a. The inner locking cone 23 aforms with the outer locking cone 22 a a positive connection, which isproduced on fitting the discharge device 1 a and serves for holding themedia reservoir in body 2 a and which also forms a second, force-limitedretention device. The limitation of the actuating force of this secondforce-limited retention device is implemented by the collar web 41 a inthe form of a tear-off ring.

[0026] In order to perform a pump stroke, in the case of the dischargedevice 1 a of FIG. 2 and in the same way as with the discharge device 1of FIG. 1, a force is exerted on the discharge device 1 a between thefinger rest 13 a and the pressure face 14 a of the pressure sleeve 5 a.As soon as the user applies an adequate pressure force to the pressureface 14 a, a locking force determined by the geometry of the lockingrecess 39 a, as well as the locking collar 40 a and the correspondingmaterial characteristics can overcome this force-limited retentiondevice. Thus, the pressure sleeve 5 a moves in discharge direction 33 aand slides along the inner guide face 38 a in intermediate sleeve 37 a.Through the solid ram 15 a provided on the pressure sleeve 5 a the outerseal 8 a is moved in discharge direction 33 a, so that there is apressure build-up in solid 17 a in solid reservoir 6 a. This built-uppressure is propagated through the solid 17 a, inner seal 7 a and liquidmedium 16 a to the piston packing 3 a. The piston packing 3 a is onlyheld in fixed manner by static frictional forces and can be displaced inthe discharge direction 33 a by overcoming said forces. Thus,simultaneously there is a synonymous movement of outer seal 8 a, solid17 a, inner seal 7 a and liquid medium 16 a. As soon as the inner seal 7a with its sealing area has passed the media reservoir edge 32 a, thereis an intermixing of the solid 17 a with the liquid medium 16 a. Throughthe displacement of the piston packing 3 a in the discharge direction 33a, the latter is penetrated by the riser pipe cutting edge 19 a. Shortlybefore the riser pipe 9 a has completely penetrated the piston packing 3a, a stop collar 42 a of the pressure sleeve 5 a engages positively on afront face 43 a of the intermediate sleeve 37 a facing the pressuresleeve 5 a. Thus, initially there is no further pressure build-up in themixture of liquid medium 16 a and solid 17 a and the riser pipe 9 a isstill not in contact with the mixture in the media reservoir. Only onovercoming a minimum actuating force leading to a tearing off of thecollar web 41 a from the intermediate sleeve 37 a, is the piston packing3 a completely penetrated by the riser pipe 9 a and the intermediatelyformed mixture of liquid medium 16 a and solid 17 a can escape in suddenbursts into the environment through media channel 12 a. The liquid ram18 a with its piston pressure face 26 a acts on a front face of thepiston packing 3 a facing the nozzle 10 a and places under pressure themixture largely located in the liquid reservoir 4 a until a front stopface 25 a of the liquid reservoir 4 a runs up onto a not shown stop inthe body. Thus, the pump stroke is at an end and the mixture of liquidmedium 16 a and solid 17 a has been discharged, apart from a residualquantity.

[0027] The media reservoir, which is not further designated and which isshown in FIG. 3 comprises a cylindrical glass tube with a frontallyarranged, outwardly directed, circumferential collar, which has aprecisely determined external diameter on a guide face 21 b providedcentrally with respect to a cylinder centre axis. On an inwardly facingcylindrical surface 24 b of the liquid reservoir 4 b is provided aninsertion cone 44 b, which narrows from a front stop face 25 b of theliquid reservoir 4 b to a not designated internal diameter of the liquidreservoir 4 b. On the front face of the liquid reservoir 4 b remote fromthe circumferential collar is provided a stagewise, exactly determinedinternal diameter, which is provided for receiving a solid reservoir 6 bin the form of a cylindrical glass tube. The solid reservoir 6 b, whichat least stagewise has an external diameter precisely matched to theinternal diameter of the liquid reservoir 4 b, forms together with thelatter a superimposing area 31 b. On a not further designated stepformed by the diameter difference between liquid reservoir 4 b and solidreservoir 6 b is provided a joining area 27 b, which in particularresults from the laser welding of the two cylindrical glass bodies. On afront face of the solid reservoir 6 b facing the liquid reservoir 7 b isprovided a sharp-edged step shoulder 34 b, which also results from thediameter difference between liquid reservoir 4 b and solid reservoir 6b.

[0028] Other variants of the discharge device according to the inventioncan be implemented as double or multiple dosing systems. This does notlead to functional areas essential to the invention being changed.

1. Discharge device (1, 1 a) for at least one medium (16, 16 a, 17, 17a) with a media reservoir, a pumping device and a discharge opening (10,10 a), wherein the media reservoir has at least two media reservoirsections (4, 4 a, 4 b, 6, 6 a, 6 b) positioned rigidly with respect toone another and which pass into one another in their interior through astep shoulder (34, 34 a, 34 b).
 2. Discharge device according to claim1, wherein the step shoulder (34, 34 a, 34 b) has a sharp,circumferential edge (32, 32 a, 32 b).
 3. Discharge device according toclaim 1, wherein the media reservoir sections (4, 4 a, 4 b, 6, 6 a, 6 b)are formed by two separate hollow bodies, which are superimposed over aportion of their length and which are tightly interconnected in thesuperimposing area (31, 31 a, 31 b).
 4. Discharge device according toclaim 1, wherein at least one media reservoir section (4, 4 a, 4 b, 6, 6a, 6 b) is made from a crystalline or amorphous material and has analmost smooth inner wall (24, 24 a, 24 b, 35, 35 a, 35 b).
 5. Dischargedevice according to claim 3, wherein an outer contour of the innerhollow body (6, 6 a, 6 b) is at least stagewise matched to an innercontour of the outer hollow body (4, 4 a, 4 b).
 6. Discharge deviceaccording to claim 3, wherein the at least two hollow bodies (4, 4 a, 4b, 6, 6 a, 6 b) are integrally joined in the superimposing area (31, 31a, 31 b).
 7. Discharge device according to claim 5, wherein at least thesuperimposing area (31, 31 a, 31 b) of at least one hollow body (4, 4 a,4 b, 6, 6 a, 6 b) is cylindrically shaped and in particular has a scarfjoint.
 8. Discharge device according to claim 1, wherein each mediareservoir section (4, 4 a, 4 b, 6, 6 a, 6 b) has a chamber separate fromthe adjacent media reservoir section (4, 4 a, 4 b, 6, 6 a, 6 b) for ineach case one medium (16, 16 a, 17, 17 a).
 9. Discharge device accordingto claim 1, wherein in at least one sealing area (36, 36 a) is providedon an inner wall (24, 24 a, 24 b) of a media reservoir section (4, 4 a,4 b, 6, 6 a, 6 b) facing the media chambers a circumferential shape forreceiving an at least stagewise spherical sealing element (3, 3 a, 7, 7a, 8, 8 a).
 10. Discharge device according to claim 1, whereinconcentrically arranged, cylindrical glass tube sections are provided ashollow bodies (4, 4 a, 4 b, 6, 6 a, 6 b) and which are in particularlaser welded together in the superimposing area (31, 31 a, 31 b). 11.Discharge device according to claim 1, wherein at least oneforce-limited retention device (20, 39 a, 40 a, 41 a) is provided on thepumping device and prevents a pump stroke below a clearly defined forcelevel.
 12. Discharge device according to claim 11, wherein force-limitedretention devices (20, 39 a, 40 a, 41 a) with different locking forcesare provided for a clearly defined sequence of individual pump strokesteps.